Apparatus for cleaning perforations



NOV. 6, 1951 3, BROWN 2,574,141

APPARATUS FOR CLEANING PERFORATIONS I Original Filed Oct. 7, 1946\gllllmll w 7 Iumu Patented Nov. 6, 1951 APPARATUS FOR CLEANINGPERFORATIONS Howard C. Brown, Bakersfield, 'Calif., assignor to B. & B.OilTool 00., Bakersfield, Calif., a partnership Original applicationOctober 7, 1946, Serial No. 701,644. Divided and this application May24, 1948, Serial No. 28,942

13 Claims.

My'invention relates to .oil well development and more particularly toimproved apparatus for cleaning perforations :in an oil well liner.

It, is a division of my application for United States Letters Patentbearing Serial Number 701,644, filed October 7, .1946, for Method andApparatus for Cleaning Perforations, "now Patent No. 2,464,669.

In the usual course of producing oil from an oil Well, the perforationsin the liner which serve to strain undesirable materials from theflowing oil eventually become clogged with such material. The materialwhich clogs the perforations in the liner may originate in any number ofdifferent sources such as the rotary circulating mud deposits from theoil strata and scale or corrosion arising from chemical action on theliner. Such accumulative clogging is inevitable even under the mostfavorable operating conditions, thus necessitating a periodic cleaningof the perforations in order to maintain the production rate and thepotential of the well.

The most common classes of procedures for cleaning the linerperforations that have been used heretofore are: methods involvingchemical procedures and methods involving hydraulic procedures andmethods involving mechanical procedures. Each of these classes ofprocedures offers its own advantagesbut frequently the difficulties ofone requires the use of another, thus necessitating an extended shutdown period for the well.

Accordingly, it is a general object of my invention to provide apparatusfor cleaning the perforations of an oil well liner which combines amechanical and a hydraulic procedure in order to clean the perforationsefiectively.

Another general object of my invention is to provide apparatus forcleaning the perforations of an oil well liner which combines amechanical and a chemical procedure in order to clean the perforationsmore effectively.

Another object of my invention is to provide a device for cleaning theperforations of an oil well liner which includes a plurality of cleaningmembers adapted 'to be projected through the perforations into :anymaterial clogging the 'perforations with means carriedby the deviceadapted to pump fluid "through the perforations upon reciprocation ofthe device within the liner.

Another object of my invention is to provide a device for cleaning theperforations of an oil well liner with :a plurality of cleaning memberswhich may be readily projected through the perforations :order to breakup any material ;clogging them, together with means for sealing off aportion of the annular space between the device and the liner in whichit is'usedin order to facilitate the simultaneous forcing of fluidthrough the perforations in order to disintegrate or wash away thematerial, or both.

:Another object of my invention is to provide a device for cleaning theperforations of an oil Well liner with a plurality of cleaning memberswhich may be readily projected through the perforations to break upmaterial clogging the perforations, together with means for sealing off-a portion .of the space between the device and the oil well liner inwhich it is used for subjecting the .sealed off portion to a fluidaction, together with means for by-passing fluid past such sealed offportions .inorder to reduce excessive resistance to movement of thedevice in the oil well liner created by the sealingaction.

Another object of my invention is to provide a device for cleaning theperforations of an oil well liner in the form of a hollow barrel havingopenings in the side walls thereof provided with cutting blades whichare normally urged outwardly through the openings.

A further object of my invention is to provide a device for cleaningvthe perforations of an oil well liner in the .form of a hollow barrelhaving openings in the walls thereof through which cleaning members areresiliently urged in order to .cut material clogging the perforations ofthe linerat the same time that fluid is forced through such openings andthrough the perforations;

In accordance with my invention I provide a perforation cleaner carryingcleaning members such as cutting blades which are bodily movable towardsor away from the carrier, with means for forcing fluid through theperforations through which the blades are projected. In one form of myinvention the region supporting the cutting blades and the regionincluding the pumping means are coextensive or at least overlap. Whenusing this latter form of my invention the material clogging theperforations of an oil well liner may be subjected to the simultaneousaction of mechanical cutting forces and hydraulic forces 'or to thesimultaneous action of mechanical cutting forces and chemical treatment.In another form of my invention the cutting blades are installed in onesection of the cleaner and the pumping means in another. In this form,the cutting action of the blades and the hydraulic or chemical action ofthe pumping fluid, or both, are applied to the material clogging some;of "the perforations alternatively. By

combining in a single operation mechanical and hydraulic or chemicalaction to remove material clogging the perforations of an oil wellliner, my invention makes possible more rapid and thorough removal ofsuch materials from the perforations. By subjecting the materialclogging the perforations to a combined mechanical and hydraulic actionthe material broken up by the mechanical action is dislodged and washedaway quickly, permitting other material to fall in its place this alsobeing subjected to similar mechanical and hydraulic action immediatelythereafter. By subjecting the material clogging the perforations to acombined mechanical and chemical action the effect of each in breakingup or disintegrating such material is greatly accelerated by the other.In particular by penetrating the material blocking the perforationsmechanically with the blades at the time that acid is being applied veryeven distribution of acid throughout the formation is attained. In orderto carry out my invention, I have designed perforation cleaners ofsimple, rugged construction and relatively low cost which permit theattainment of the results desired at a great saving in operating costand operating time.

The foregoing and other objects and advantages of my invention will bemore readily understood by reference to the following description ofspecific apparatus embodying my invention. While the main features of myinvention have been set out in broad terms in the statement thereofabove, other features of my invention which are incorporated in theembodiments specifically illustrated and described herein will becomeapparent from a reading of the following description in conjunction withthe accompanying drawings wherein:

Figure 1 is a side elevational view of a preferred embodiment of myinvention;

Figure 2 is a side elevational view of another preferred embodiment ofmy invention;

Figure 3 is a detailed sectional view of the barrel forming part of thedevice of Figure 1 and illustrating a preferred form of cleaningimplement; and

Figures 4, 5 and 6 are schematic diagrams used in explaining theoperation of the cleaning implement.

The well liner perforation cleaning device ilmechanical cleaning memberspreferable in the form of rigid blades I6 extend laterally from thebarrel through apertures I8 in the side wall thereof. These blades I6are arranged on the barrel both for pivotal movement in a plane parallelto the axis of the barrel and for bodily shifting towards and away fromthe barrel. Preferably the blades and the apertures through which theyproject, are distributed more or less evenly and spirally along thelength of the barrel and more or less evenly about its periphery. Theblades are of such length that they may be extended to outer positionsin which their pointed ends project outwardly beyond the cylindricalsurface defined by the peripheries of the packmg cups.

The carrier is adapted for attachment to the lowermost end of a stringof hollow drill pipe 20 by means of a coupling 22. The lowermost endofthe barrel I0 is provided with an orifice 26 which communicates withthe interior Qf $1 4 barrel through an inwardly opening ball check valve25.

Referring to Figure 3, there is illustrated a. preferred arrangement ofcleaning implement embodied in this form of my invention. This cleaningimplement comprises a cleaning member in the form of a blade l6 having ahead 26 thereon which is mounted within an enlarged bore 28 with theblade extending outwardly through a narrow longitudinal slot 30. A coilspring 32 is arranged transversely of the cavity 33 in the interior ofthe barrel I0 and is provided with an end plate 34 to normally urge thehead 26 outwardly against a shoulder 36 formed between the cylindricalbore 28 and the slot 30. The spring is held compressed in that positionby means of a threaded plug 38 which is screwed into a threaded bore 40in the wall of the barrel I0 directly opposite the first mentioned bore28. The cuttin blade I6 is of flat rigid construction terminating in asharp point at the outer end thereof. The head 26 is of hexagonalcross-section in the longitudinal plane of the barrel, the two verticalsides being elongated and the upper and lower ends being in the form ofright angle points. Each of the cleaning implements projecting bladesthrough the apertures of the barrel I0 is of similar construction.

Considering the action of the cutting blades, normally the blades I6project radially outward and upward from the barrel I0 as the device islowered in a well liner for the first time, until the tool reaches thebottom of the first downward stroke. Then the tool is elevated and whena blade reaches the edge of a perforation ll of the liner 42, it may beforced directly outward and upward through the perforation slot, digginginto any material directly behind the perforation slot by the combinedforce of the elevation of the barrel I 6 and the action of thecorresponding spring 32, if the material is soft enough.

Elevation of barrel ID causes bore 28 to lift up against the inner end26 of blade I6, thus causing blade I6 to be driven into the formation.This is a frictional metal to metal drive which exerts great leverageforce against blade I6. As the raising of the device continues the bladeI6 may break up such material by a cutting and digging arc action. Whenthe blade reaches the upper edge of the perforation slot the upper edgeof this slot arrests further upward move ment of the blade and acts as afulcrum to lever the blade outwardly and in a downward arc, and head 26is rocked inwardly against the action of the spring 32 until blade I6 iscompletely withdrawn from the perforation in a downwardly inclinedposition relative to the axis of the barrel, thus completing the are.When the downwardly inclined blade next registers with a perforationslot on this upstroke it will rock back to its radial position and digand out into the material clogging that second perforation if thematerial is not too hard. One or both of these cutting actions occurseach time that a blade I6 registers with a perforation slot whenever thedevice is raised or lowered in the well, the lower ing actions, afterthe first one, being the reverse of the raising actions described above.

This raising and lowering is continued until the perforations beingworked on are clean. 0rdinarily the preferred method is to clean apredetermined length of liner by raising and lowering within that lengtha predetermined number of tini s- Then t e ne t section of liner of thatperforations Li I.

predetermined length is cleaned and this is repeated until the entireperforated area is cleaned and the job is finished.

In using this device to clean the perforations of a well liner G2, whichhave become clogged by the accumulation of any material in theperforations, the device is lowered into the well upon the bottom of astring of tubing or drill-pipe. As it is being lowered, the packing cupsestablish seals with the inner wall of the liner, thus sealing Off anannular ring space as between the barrel and the liner and between theupper and lower pairs of packing cups. As the device is lowered into thewell, the inwardly opening check valve 25 at the bottom of the barrelopens, admitting fluid into the barrel and thence into the tubing ordrill pipe, thus reducing the resistance to the iowering of the devicein the well created by the sea-ling action of the packing cups. As thedevice is lowered in an unperforated portion of the liner the weight ofthe drill pipe actting downwardly forces the fluid within the linerbelow upper cups l2 to flow into the apertures E8 in the side of thebarrel H! from the annular ring space M and thence inside the barrel i0past the upper packing cups l2 into the tubing or drill pipe 20.

As the lowering of the device continues beyond the point where the upperpacking cups l2 have passed some of the perforations, fluid is forcedoutward through the perforation slots 4! into the space behind the linerand thence upwardly and back into upper annular space 46 through theliner perforations above .the upper packing cups l2.

When the device is subsequently .raised in the well, the check valve 25closes preventing egress of fluid from the interior of the barrelthrough its bottom opening 24. Thus,.closing valve 25 as the device israised causes the fluid within the tubing or drill pipe 253 to bedischarged outwardly through the apertures I8 in the barrel l8 into theannular ring space 44 between the packing cups and thence outwardlythrough the .At the same time well fluid which is located in the annularspaces 44 and iii between the tubing 01' drill pipe and the well lineris forced outwardly through the perforations above the lower packingcups l4 through perforation slots 4| into the space outside the wellliner. All of the fluid thus forced out of the perforations above thelower packing cups flows downwar ly outside of the liner and back intothe liner through perforations below the lower packer cups I4.

This method and result is reversed on each downward stroke.

Thus, as the device is raised and lowered in the well the packing cupsand the check "valve cooperate to pump fluid through the perforations atthe'same time that the blades are working in them, and thus they aid thecutting blades in removing material that is clogging the perforations.It is to be noted that both in the raising and the lowering of thisdevice in the well, fluid is forced outward through the perforations Hin which the blades are working, thus reducing the likelihood of brokenup material entering the annular ring space 44 between the packing cups.While the fluid flow action may vary somewhat from time to time,according to circumstances, it will be understood that my invention isnot limited to the specific fluid flow action just described; this fluidflow action being set forth merely to facilitate the understanding ofthe operation of this device in cleaning the perforat-ions.

.Also this flow of fluid surging out and in through perforation slots 4|may be effected directly from the surface by forcing fluid underpressuredown through pipe *20 and slots la in barrel NJ between cups l2 and Hiinto space 4'4 and thence through slots 4| into the space outside thelinerand thence up past cups i2 and back through perforations 4| aboveupper cups [2 into space 46 and :on up to the surface if a completereturn of circulating fluid is desired.

In a preferred method of utilizing my invention, a chemical substance,such as acid, which is reactive with material likely to be clogging theperforations may be injected into the well by any method describedabove. When this acid is so positioned within the well, it is forced toflow through the perforations simultaneously with the cutting by theblades l6 of material clogging the perforations by the same method asthe non-acid fluid described above.

The material clogging the perforations is thus rapidly disintegrated bythe combined mechanical, fluid and chemical action. This throws the acidfarther out through perforation slots 4| than is accomplished byordinary acid flushing methods.

Thus, instead of the acid being applied at the mouth of the perforationslots 4|, as in previous methods, my .method projects the acidimmediately beyond slots Ail to the sand face outside the liner by theassistance of the combined knife and hydraulic action.

In another embodiment of my invention illustrated in Figure 2 I utilizea carrier 50 in the form of a solid cylindrical body 52 at the lower endthereof and a hollow tubular portion 54 at the upper end thereof. Aplurality of cutting blades 56 is projected outwardly of the cylindricalbody 52 through slots 58. These blade assemblies are of the same generaltype as that herein-before described in detail (see Figure 3) exceptthat the-spring is arranged in a single radial bore that extendssubstantially all the way through the cylindrical body from one sidethereof toward the other and there is no central cavity within orpassage through the body 52 which intersects this bore. Accordinglythese blades 56 likewise are adapted for pivotal movement in a planeparallel to the axis of the cylindrical body and for bodily shiftingtowards and away from the body, like blades l6, described above.

The tubular portion 54 is adapted at its upper end for attachment to thelowermost end of a string of tubing or drill pipe 58 by means of acoupling 60. This tubular portion 54 is provided with an orifice 62 inthe side wall thereof intermediate its ends and has mounted thereonopposed upper and lower pairs of packing cups 64 and '66, arrangedrespectively above and below the orifice 52. A by-pass pipe 68 arrangedwithin this tubular position 5% terminates at the lower end in the loweropening 10 beneath the lower pair .of packing cops 66 and at the upperend in an upper opening l2 above the upper packing cups ea.

As this device is lowered in an oil well the packing cups contact theliner of the well and seal off an annular ring space 1 3 between thetubular portion of the carrier and the well liner and cups 64 and 66.This annular space communicates with the interior of the drill pipethrough the orifice 62 in the wall of the tubular portion. As the deviceis lowered in a portion of the liner having no perforations therein,some of the fluid in the space 16 in the liner beneath the device isforced through the by-pass pipe into the annular space 18 between thedrill pipe and the liner above the packing cups 64 and 66, and someleaks past the lower packing cups 66 into the annular ring space 14 andthence through the orifice 62 into the tubular member and thence intothe drill pipe '58. Finally when the blades 56 of the device encounterperforations in the liner the blades are projected outwardly through theperforations into any material clogging the perforations breaking upthis material in the manner hereinbefore described.

Fluid is forced outward through the perforations in the portion of theliner between the two sets of packing cups by pressure from the surfaceand thence outside the liner and then inwardly through the perforationsabove or beneath the packing cups. Finally during the raising of thedevice into a portion of the liner which is not perforated fluid abovethe packing cups 64 flows into the region below the packing cups 66through the b-y-pass pipe 68.

During the reciprocation of this device upward and downward within theperforated portion of the liner, fluid is forced from the surfacethrough pipe 58 to the perforations in which the blades have worked.This flushing and washing action thus cooperates with the digging andcutting action of the blades to accelerate the removal of materialclogging the perforations far beyond the speed with which such removalcould be accomplished by either action alone or by both actions inseparate consecutive operations, thus effecting a great saving in timeand cost. Clearly, of course, chemical action could also be added toaccelerate the cleaning of the perforations still further in accordancewith the principles hereinbefore set forth.

From the foregoing description of my invention it will be clear that Ihave provided a well liner perforation cleaner which combines andimproves the advantages of mechanical, chemical and hydraulic well linerperforation cleaners heretofore available, The use of my Well cleaner isof advantage both in initial completion and subsequent treatment of awell. When used in initial completion of a well the Opening and cleaningof all perforations of a well liner is assured through the removal ofthe mud cake and stray cement from the perforations, thus exposing thecomplete sand face of the formation from which production is desired tothe perforated liner and assuring uniform distribution of fiow into thewell from the formation. The opening of all of the perforations promotesthe even distribution of the washing action through all possiblechannels throughout the length of the liner rather than through the fewchannels which happen to be weakest at the outset, thus precluding thepossibility of the flow concentrating in a small portion of this linerthereby producing corresponding high velocity of flow in that regionwith the resultant excessively high debris carrying capacity associatedwith such high fluid velocity. The form of my invention which involveschemical treatment has the advantage of assuring an even distribution ofchemicals through the zone to be treated and the subsequent thorough andrapid removal of the spent chemical after the treatment has beencompleted.

The use of my perforation cleaning system is particularly advantageouswhen preparing a well for a potential test as the thorough cleaning ofthe perforations permits the well to operate at its maximum rate.Cleaning of the space behind the well liner may also be accomplished bymy method, thus facilitating the preparation of a liner for withdrawalfrom the well. My well cleaning system is also advantageous for use inopening up the perforations of a liner to facilitate the evendistribution of cement or plastic in a plugging 'job.

While particular arrangements and specific details have been set forthin this specification for the purpose of completely illustrating twopreferred embodiments of apparatus with which the method of my inventionmay be used and for completely illustrating the principles involved inits operation, it is to be understood that my invention in its broaderaspects is not limited to such details, reference being made to thefollowing claims for a definition of my invention in both its broad andnarrow aspects.

I claim:

1. A device for cleaning perforations in an oil well liner comprising acarrier having a longitudinal cavity therein open at one end adapted tobe supported upon the bottom of a string of hollow pipe; a plurality ofcleaning members extending laterally from the carrier, each of saidcleaning members being fioatingly mounted within an enlarged borearranged transversely of said cavity in the carrier for both pivotalmovement and bodily shift towards and away from the car rier; a coilspring mounted in each said transverse bore for urging said cleaningmembers laterally outward from the carrier towards extended positionsthereby causing the cleaning members to enter perforations in saidliner; means defining an orifice in the carrier wall for establishingcommunication between th interior of the carrier and the annular spacebetween the carrier and said liner; and means including a packingelement adapted to operate as a seal in the liner for pumping fluidalong a path passing through said orifice and said annular space andperforations in said liner.

2. A device for cleaning perforations in an oil Well liner comprising acarrier adapted to be supported upon the bottom of a string of hollowpipe and having a longitudinal cavity therein open to the interior ofsaid pipe; a plurality of cleaning members extending laterally from thecarrier,

- otal movement and bodily shift towards the carrier; a coil springmounted in each said transverse bore for urging said cleaning memberslaterally outward from the carrier towards extended positions therebycausing the cleaning a members to enter perforations in said liner; a

' pair of opposed packer elements mounted upon said carrier forestablishing seals between said carrier and said liner above and belowsaid cleaning members; means including an orifice in the carrier wallbetween the packing elements for establishing communication between theinterior of said pipe and the annular space surrounding the carrierbetween the packing elements.

3. A device for cleaning perforations in an oil well liner comprising acarrier adapted to be supported upon the bottom of a string of hollowpipe; a plurality of cleaning members extending laterally from thecarrier at the lower portion thereof, each of said cleaning membersbeing floatingly mounted within an enlarged bore arranged transverselyof said carrier in the carrier gratin for both pivotal movement andbodily shift towards and away from the carrier; yielding coil springmeans mounted in said transverse bores for urging said cleaning memberslaterally outward from the carrier towards extended positions therebycausing the cleaning members to enter perforations in said liner; a pairof opposed packer elements mounted upon said carrier at the upperportion thereof for e'stablishing'a pair of seals between said carrierand said liner; and means including an orifice in the carrier wallbetween the packing elements for establishing communication between theinterior of, said pipe and the annular space surrounding the carrierbetween the packing elements. v

4. A device for cleaning perforations in an oil well liner comprising acarrier adapted to be supported upon the bottom of a string of hollowpipe; a plurality of cleaning members extending laterally from thecarrier at the lower portion thereof, each of said cleaning membersbeing fioatingly mounted within an enlarged bore arranged transverselyof said carrier in thecarrier. for both pivotal movement and bodilyshift towards the carrier; a coil spring mounted in each said bore forurging said cleaning members, laterally outward from the carrier towardsextended positions thereby causing the cleaning members to enterperforations in said liner; a pair of opposed packer elements mountedupon said carrier at the upper portion thereof, for establishing a pairof opposed seals between said carrier and said liner; means including anorifice in the carrier wall between the opposed packer elements forestablishing communication between the interior of said pipe and theannular space surrounding the carrier between the 'opposed packerelements; and means establishing a fluid by-pass passage in saidcarrier, said passage having an opening located above and anopeninglocated below said opposed packer elements.

5. A device for cleaning perforations-in an oilwell liner comprising acarrier adapted to be supported upon the bottom of a string of hollowpipe; a plurality of cleaning members extending laterally from thecarrier, each of said cleaning members being floatingly mounted withinan enlarged bore arranged transversely of said carrier in the carrierfor both pivotal movement and bodily shift towards the carrier; a coilspring mounted in each said transverse bore: for urging said cleaningmembers laterally outward from the carrier towards extended positionsthereby causing the cleaning members to enter perforations in saidliner; a pair of opposed packer elements mounted upon said carrier forestablishing seals between said carrier and said liner above and belowsaid cleaning members; means including an orifice in the carrier wallbetween the packer elements for establishing communication between theinterior of said pipe and the annular space surrounding the carrierbetween the packer elements; and means establishing a fluid by-passpassage in said carrier, said passage terminating in a pair of openingslocated respectively above and below said packer elements.

6. A device for cleaning perforations in an oil well liner comprising acarrier adapted to be supported upon the bottom of a string of hollowpipe; a plurality of cleaning members extending laterally from thecarrier, each of said cleaning members being floatingly mounted withinan enlarged bore arranged transversely of said carrier in the carrierfor both pivotal movement and bodily shift towards the carrier; a coilspring mounted in each said transverse, bore for urging said: cleaningmembers laterally outward from the carrier towards extended positionsthereby causing the cleaning members to enter perforations said liner; apair of opposed packer elements mounted upon said carrier forestablishing seals b'etw'een'said carrier and said liner above and belowsaid cleaning members; and means including an orifice in the carrierwall between the packer elements for establishing communicationbetweenthe interior of the pipe and the annular space. surrounding thecarrierbetween the packer elements.

7; A device for cleaning perforations in an oil well liner comprising ahollow barrel adapted to be supported at its upper end upon the bottomof a string of hollow pipe, and having a plurality of apertures in thewall thereof for establishing communication with the interior of saidpipe; a plurality of cleaning members extending laterally through saidapertures, each of saidcleaning members being noatingly mounted withinan enlarged bore arranged transversely of said barrel in the barrel forboth pivotal movement in said openings and bodily shift into and out ofsaid openings; a coil spring mounted in each said transverse bore forurging said cleaning members laterally outward through said aperturestowards extended positions thereby causing the cleaning members toenter'saicl perforations; means for sealing off the space bet'ween theapertured. portion of the barrel and the ad.- jacent portion of a linerwhich it is working whereby fluid may be pumped along paths passtom of astring of hollow pipe and having a plurality of openingsin the wallthereof for establishing communication with the interior of said pipe; aplurality of cleaning members extending laterally through said openings,each of said cleaning members being floatingly mounted within anenlarged bore arranged transversely of said barrel in the barrel forboth pivotal movement in. said openings and bodily shift into and out"of' said openings; a coil spring mounted in each said transverse borefor urging said cleaning members laterally outward through said openingstowards extended positions thereby causing the cleaning members to enterperforations in said liner; and a pair of packer elements respectivelymounted on opposite sides. of said plurality of cleaning members forestablishing seals between saidbarrel and; said liner at positions aboveand below said plurality of cleaning members; and' an inwardly opening.

check valve at'the bottom end of saidb arrel for preventing flow offluid outwardly of the barrel at the bottom end thereof.

9. A' device for cleaning perforations in an oil wellliner comprising ahollow barrel adapted tobe supported at its. upper end upon the bottomof a string of hollow pipe and having a plurality of apertures in thewall thereof and another opening at the bottom thereof for establishingcommunication with the interior thereof; a-plii'- rality of cleaningmembers extending laterally through said apertures, each of saidcleaning members being floatingly mounted within an enlarged borearranged transversely of said barrel in the barrel for both pivotalmovement in said openings and bodily shift into and out of said opening;yielding coil spring means mounted in said transverse bores for urgingsaid cleaning members laterally outward through said apertures towardsextended positions thereby causing the cleaning members to enterperforations in said liner; a packer element mounted on said barrelbetween said apertures and said opening, said packer element beingadapted to act as a piston in said liner; and an inwardly opening checkvalve in said barrel for causing fluid to pass through said opening inan upward direction only whereby reciprocation of said device in saidliner causes fluid to be pumped into said liner through perforationsbeneath said packer element and out of said liner through perforationsabove said packer element.

10. In a device for cleaning perforations in an oil well liner, theimprovement which comprises: a hollow barrel adapted to be supported atits upper end upon the bottom of a string of hollow pipe, said barrelhaving a plurality of transverse recesses in the inner wall thereof anda plurality of vertical slots in the outer wall thereof extendingparallel to the axis of said barrel and communicating with therespective transverse recesses, said transverse recesses providing innershoulders between said transverse recesses and said vertical slots, aplurality of rigid cutting blades extending laterally outward throughsaid slots, each of said blades being provided with an enlarged'headwithin the corresponding transverse recess, thickness of said enlargedheads being greater than the width of said vertical slots, and yieldingcoil spring means within the said respective transverse recesses forurging said heads laterally outward toward the respective shoulders ofsaid transverse recesses; said cutting blades and said yielding coilspring means being so arranged'as to force said blades into materialobstructing said perforations upon raising and lowering said device insaid liner.

11. A device for cleaning perforations in an oil well liner comprising:a hollow barrel adapted to be supported at its upper end upon the bottomof a string of hollow pipe, said barrel having a plurality of transverserecesses in the inner wall thereof and a plurality of vertical slots inthe outer wall thereof communicating with the respective transverserecesses, said transverse recesses providing inner shoulders betweensaid transverse recesses and said vertical slots; a plurality ofcleaning members extending laterally outward through said verticalslots, each of said cleaning members being provided with an enlargedhead within the corresponding transverse recess the thickness of saidenlarged heads being greater than the width of said vertical slots;-

yielding coil spring means within the said transverse recesses forurging said heads laterally outward toward the respective shoulders ofsaid transverse recesses, said cleaning members and said yielding coilspring means being so arranged as to force said cleaning members intomaterial obstructing said perforations upon raising and lowering saiddevice in said liner; and a pair of packer elements mounted on saidbarrel on opposite sides of said plurality of cleaning members.

12. A device for cleaning perforations in an oil well liner comprising:a hollow barrel adapted to be supported at its upper end upon the bottomof a string of hollow pipe, said barrel having a plurality of transverserecesses in the inner wall thereof and a plurality of vertical slots inthe outer wall thereof communicating with the respective transverserecesses, said transverse recesses providing inner shoulders betweensaid transverse recesses and said vertical slots; a plurality of cuttingmembers extending laterally outward through said vertical slots, each ofsaid cleaning members being provided with an enlarged head floatinglymounted within the corresponding transverse recess the thickness of saidenlarged heads being greater than the width of said vertical slots;yielding coil spring means within the said transverse recesses forurging said heads laterally outward toward the respective shoulders ofsaid transverse recesses, said cleaning members and said yielding coilspring means being so arranged as to force said cleaning members intomaterial obstructing said perforations upon raising and lowering saiddevice in said liner; a pair of packer elements mounted on said barrelon opposite sides of said plurality of cleaning members; and an inwardlyopening check valve at the bottom of said barrel for preventing flow offluid outwardly of the barrel at the bottom end thereof.

13. In a devicefor cleaning perforations in an oil well liner theimprovement which comprises: a hollow barrel adapted to be supported atits upper end upon the bottom of a string of hollow pipe, said barrelhaving a plurality of bores extending laterally and transversely throughthe wall thereof and a plurality of inner recesses in the inner wallthereof opposite the respective transverse bores and a plurality ofvertical slots in the outer wall thereof communicating with therespective recesses, said recesses providing inner shoulders betweensaid recesses and said vertical slots; a plurality of cutting bladesextending laterally outward through said vertical slots, each of saidcutting blades being provided with an enlarged head fioatingly mountedwithin the corresponding recess the thickness of said enlarged headsbeing greater than the width of said vertical slots; a plurality of coilsprings arranged transversely of the axis of the barrel and along therespective axis passing through said transverse bores and the opposedrecesses for urging said heads laterally outward toward the respectiveshoulders of said recesses whereby said blades are urged laterallytoward extended positions thereby causing the blades to enterperforations in said liner; and retaining means in said transverse bbores for holding said coil springs in operative positions in the saidtransverse bores.

HOWARD C. BROWN.

REFERENCES CITED The following references are of record in the file ofthis patent:

